Modeling And Operation Optimization Of Coal Pulverizing System Of Large Thermal Power Unit

Coal pulverizing system is the main subsystem of the thermal power plant. The power consumption of primary air fan and coal mills accounts for 15%-25% of the auxiliary power, and their operation conditions affect the safety and economical operation of coal pulverizing system and the boiler efficiency. It is of great significance to optimize strategy of coal pulverizing system in order to reduce power consumption of the coal pulverizing system.Steady-state models of the coal pulverizing system, including temperature and pressure of the air and powder mixture in the coal mill outlet, were built in this work. The operation data of the coal pulverizing system of Hua’neng Nanjing Jinling Power Plant were applied to validate the models. The results show a reasonable agreement between the measured data and model predictions both qualitatively and quantitatively within a 5% error margin.Coal mill and primary air fan are the main power-intensive apparatus of coal pulverizing system. There exists a load distribution optimization among the coal mills because of the power consumption property of each mill. The performance of each mill was fitted using the sampling data from the Power Plant. Dynamic programming method, which is programmed using C language, is chosen as the optimization tool to optimize the load distributions. After the load distribution optimization, the system can save 98kW、87kW、39kW、31kW、134.4kW、115.5kW of power consumptions respectively when the total fuel consumption is 280t/h、290t/h、300t/h、310t/h、320t/h、 330t/h, as compared with the average load distributions for the 1000MW unit of Huaneng Jinling Power Plant.Finally, cloud data analysis method was applied to analyze the performances of the 1000MW coal pulverizing system in Huaneng Jinling Power Plant. The relations between the unit power output and coal consumptions were plotted according to the operation data sampled from the Power Plant. Under the same power output, the coal consumption changes widely, and this means the coal pulverizing system affects the performance of boiler. It is possible to optimize the load distributions among the coal mills. Under optimal operation conditions, the boiler can be operated efficiently. The outputs of the mills in the high and low efficiency regions were compared and analyzed under the typical conditions. The impact of load distributions of coal mills on thermal economic performance of power plant was verified through the experiments. When the unit is operated under the higher load, coal mills C, D, E should first be maintained equally at high outputs, and then is followed by coal mill B at high output. Lastly, coal mill F is used to adjust the power output. The boiler is under high efficient region when the coal pulverizing system runs in this manner.